Recently, attention has been focused on a light source device which uses an LED chip as a light source (hereinafter, referred to as an “LED light source device”). The LED light source device has advantages of a longer life and less power consumption than an incandescent light bulb and a fluorescent lamp have. However, there is a limit to the amount of light outputted from a single LED chip. For this reason, in an LED light source device, multiple LED chips are normally mounted on a flexible board to obtain a necessary amount of light (for instance, refer to JP-A 2002-232009 (Kokai)).
Nevertheless, recently the LED light source devices are required to have a higher durability because applications of LED light source devices expand. Moreover, further reduction in cost is demanded because applications of LED light source devices expand.